Anyone who figured out messaging beyond “Look how bad Trump is, even Bush republicans won’t vote for him” probably wins that election. No one had a broad vision to latch for sale, and no one did anything inspiring.

A lot of places self insure, but some already buy insurance as you describe. Qualified immunity is a pretty high bar to get over, but some people do get settlements. I’d argue insurance should have to be bought by the officer, or their union to have any effect on their behavior.